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Paleo-atmosphere
Topic Started: Aug 15 2015, 07:28 PM (802 Views)
joe99
Unicellular Organism
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well since the atmosphere of the carboniferous was different and if we brought back the animals would die due to the atmosphere but where is the line for a prehistoric organism too survive in todays atmosphere 6mya? 20mya?

this is for a story im writing and I want it to be as accurate as possible
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Jinfengopteryx
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Aspiring paleontologist, science enthusiast and armchair speculative fiction/evolution writer
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I don't know if you can draw such a line, but I hope this picture helps you in case you are interested in prehistoric oxygen levels:
Posted Image
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J3st3r56
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Hm. I feel like animals that were pre-permian may struggle the most with today's atmosphere, but looking at the graph provided (thankyou Jinfengopteryx) it appears that Jurassic animals may be the most suited to today's atmosphere. (about 170 MYA to 120 MYA) which is curious because that is when animals were at their biggest overall. You would of thought that large animals means large amounts of oxygen for them, allowing higher growth rates, unless food was more abundant. I know I'm not particularly helping, but i like musing about these things. However, Carboniferous animals would not be able to breathe our atmosphere because of higher concentrations of co2 and methane and exponentially lower o2 levels.
Edited by J3st3r56, Aug 16 2015, 06:07 AM.
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joe99
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Jinfengopteryx
Aug 15 2015, 07:48 PM
I don't know if you can draw such a line, but I hope this picture helps you in case you are interested in prehistoric oxygen levels:
Posted Image
thanks for that graph
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rocking1805
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Are you sure the graph is accurate? I've read an article recently and they told that according to the latest analysis Oxigen level appears to be lower in Cretacious than today (abot 17-18% against 21% for today). So it would mean that higher level of oxigen can no more stay a reason of why dinosaurs grew so big.
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theropod
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palaeontology, open source and survival enthusiast
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And afaik they are not considered to be the reason in modern science. Sander et al. provide some discussion of this:

Quote:
 
(a) Increased oxygen content of atmosphere
All else being equal, would an increased level of atmospheric
oxygen allow the evolution of gigantic terrestrial tetrapods?
This possibility is suggested by the example discussed above
of the uniquely gigantic dragonflies of the Carboniferous
(Lighton, 2007). Hengst et al. (1996) explored this hypothesis
for sauropod dinosaurs, based on the premise of an oxygen
level of 30% or above in the Jurassic atmosphere (Landis et al.,
1996). Physically modelling respiration in the Late Jurassic
sauropod Apatosaurus, they concluded that the respiratory
system of this animal could not have delivered enough oxygen
to the tissues at today’s oxygen levels. This applied even under
the assumption that Apatosaurus had the basal metabolic rate
of a reptilian ectotherm. However, the hypothesis of Hengst
et al. (1996) is superseded by the likely presence of a bird-
like lung in sauropods and the current understanding that
oxygen levels were significantly lower in the Jurassic and
Cretaceous than today (Gans et al., 1999; Dudley, 1998;
Berner, 2006; Berner et al., 2007; see also Fig. 8) or at about
the same level (Bergman, Lenton & Watson, 2004; Belcher
& McElwain, 2008).

There appears to be some controversy, but little to suggest considerably higher oxygen levels during the mesozoic than today. Also of note is that extant whales are comparable in size to sauropods and that they can survive without problems, even with a (less efficient) mammalian respiratory system, and even well enough to hold their breath for hours in some cases.
Sauropods could reach their gigantic sizes because their body plans, uniquely efficient feeding adaptions and reproductive strategy enabled them to do so, not because there was more oxygen at their time than there is today.

I think while our atmosphere may require some getting used to for any extinct animal, most phanerozoic animals would be able to adjust to it, with the probably exception of the carboniferous, especially the large terrestrial arthropods.

Sander, P. Martin; Christian, Andreas; Clauss, Marcus; Fechner, Regina; Gee, Carole T.; Griebeler, Eva-Maria; Gunga, Hanns-Christian; Hummel, Jürgen; Mallison, Heinrich; Perry, Steven F.; Preuschoft, Holger; Rauhut, Oliver W. M.; Remes, Kristian; Tütken, Thomas; Wings, Oliver; Witzel, Ulrich (2011) Biology of the sauropod dinosaurs: the evolution of gigantism. Biological Reviews, 86 (1), pp. 117-155.
Edited by theropod, Sep 20 2015, 08:04 PM.
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